1. Field of the Invention
The invention relates to an apparatus and method for use in the field of oil and gas recovery. More particularly, this invention relates to a system having a first component, such as a detectable object or transponder, and a second component, such as sensor or sensor coil, adapted to determine when a device has passed a given point in the system.
2. Description of the Related Art
Cementing a wellbore is a common operation in the field of oil and gas recovery. Generally, once a wellbore has been drilled, a casing is inserted and cemented into the wellbore to seal off the annulus of the well and prevent the infiltration of water, among other things. A cement slurry is pumped down the casing and back up into the space or annulus between the casing and the wall of the wellbore. Once set, the cement slurry prevents fluid exchange between or among formation layers through which the wellbore passes and prevents gas from rising up the wellbore. This cementing process may be performed by circulating a cement slurry in a variety of ways, as described in parent U.S. patent application Ser. No. 10/120,201, entitled xe2x80x9cApparatus and Method of Detecting Interfaces Between Well Fluids,xe2x80x9d filed Apr. 10, 2002, by Robert Lee Dillenbeck and Bradley T. Carlson, attorney docket number 10286.0312.NPUS00, hereby incorporated herein in its entirety by reference.
Generally, in a conventional cementing operation, a cementing head is attached to the upper portion of the casing. A wiper plug is inserted into the cementing head. Liquid cement slurry is pumped down the cementing head forcing the wiper plug through the cementing head and into the casing. Once the desired amount of cement has been pumped inside the casing, another wiper plug, which had also been pre-inserted inside the cementing head, is released from the cementing head. A non-cementacious displacement fluid, such as drilling mud, is then pumped into the cementing head thus forcing the second wiper plug into the casing.
It is important to determine that each wiper plug has been properly xe2x80x9claunched,xe2x80x9d i.e. that each wiper plug has left the cementing head. It is not uncommon for these wiper plugs to turn sideways and become lodged in the casing. If the plugs become lodged, excessive pressures may build up in the cementing head. Further, if the wiper plugs turn sideways, the cement may mix with the non-cementacious displacement fluid such as drilling mud. If this happens, the resulting cement may be contaminated to the point that a remedial cementing job may be required. Such remedial cementing jobs are time consuming, expensive and generally not as effective as a primary cementing job.
To determine if each wiper plug has been successfully launched, it is known to attach a wire to each wiper plug. The length of the wire corresponds to the length of the cementing head. As the wiper plug descends into the cementing head, the wire follows. Operators at the surface may visualize the movement of the wire which lets them know the wiper plug is moving down the cementing head. When the wiper plug enters the casing, the end of the wire enters the cementing head and no further wire is visible at the surface. Thus, in some applications, it is known to attach a piece of wire to the rubber wiper plug. However, this system requires an operator to monitor the wire at the surface. Further, this system is subject to defects because the wires may become accidentally separated from the wiper plug before the wiper plug reaches the casing. In this situation, the operator cannot ascertain whether the wire is loose or whether the wiper plug is lodged. Thus, there is a need for an apparatus and method for determining for certain that these wiper plugs have been properly launched.
Another common operation in well drilling and completion operations is the isolation of particular zones within the well. In some applications, such as cased-hole situations, conventional bridge plugs can be used. In other applications, it is possible to prevent the flow of fluids into the casing or to block off a particular zone in the well as follows. The casing will contain perforations in its walls at the horizontal level of a particular zone. The perforations are of known diameter. Sealing balls, having a diameter slightly larger than the perforations, are launched into the casing as follows. The sealing balls are loaded into a commercially available ball launcher or ball injector, such as the model GN201 or 202 by BN Machine Works of Calgary, Alberta. The ball injector periodically inserts a sealing ball into fluid flowing through an intermediate pipe to which the ball launcher is inserted. Once inserted into the intermediate pipe, the sealing balls travel through the conduit and finally are launched into the casing. The sealing balls then travel down the casing until the become lodged in the perforations.
As with the wiper plugs discussed above, occasionally the sealing balls will not properly launch. In some situations, the ball launcher or injector becomes jammed and the ball never leaves the injector. In other situations, an operator may fail to load any or a sufficient number of balls into the injector. In other situations, the injector may run out of balls. The result is that the operators erroneously believe the perforations are properly plugged and the desired zone is blocked off.
Prior art methods may also rely upon changes in pressure noticed at the surface to signal the arrival of the sealing balls in the perforations. However, these systems only signal the arrival of the sealing balls at the final destination; not the launch of the sealing balls. Thus, valuable time may elapse before it is realized that the sealing balls were improperly launched.
Thus, there is a need for a device that accurately verify that the sealing balls were properly launched from the ball injector.
The invention relates to a system and a method for detecting the launch of a device. In some embodiments, a system for detecting the launching of a device, is described having a first component disposed within the device, the device adapted to travel through a conduit and into wellbore, a first end of the conduit in fluid communication with an upper end of the wellbore. The system includes a second component, the first component and the second component adapted to be in communication with each other as the first component becomes substantially adjacent the second component thus detecting the launch of the device. The first component may be a sensor and the second component may be a detectable object, or the first component may be a detectable object and the second component may be a sensor.
The device being launched may be a wiper plug or a sealing ball. The the conduit may be connected to an upper end of a casing within the wellbore, and the second component is disposed substantially adjacent the first end of the conduit. In some embodiments, the sensor is a sensor could mounted within the outer diameter of the first end of the conduit. The detectable object may be a transponder adapted to send a Radio Frequency Identification signal to the sensor coil, the transponder modulating to send a unique identification number to the sensor coil. In other aspects, the transponder resonates at a frequency, the sensor coil being tuned to resonate at the frequency of the transponder. The frequency of the transponder may be 134.2 kHz. In some embodiments, the system may include host electronics in communication with the sensor coil, the host electronics displaying the unique identification number of the transponder.
In some embodiments, the device being launched is a sealing ball and the first end of the conduit is connected to the upper end of the wellbore by an intermediate pipe. The second component is disposed on the intermediate pipe. In some embodiments, the sensor further comprises a sensor coil adapted to be mountable within the inner diameter of the intermediate pipe. In others, the sensor further comprises a sensor coil adapted to be mountable around an outer perimeter of the intermediate pipe.
In some aspects, the detectable object is a transponder adapted to send a Radio Frequency Identification signal to the sensor coil. The transponder may modulate to send a unique identification number to the sensor coil, for instance at a frequency, the sensor coil being tuned to resonate at the frequency of the transponder. In some aspects, this frequency is 134.2 kHz. The system may include host electronics in communication with the sensor coil, the host electronics displaying the unique identification number of the transponder. The transponder may be implanted into the sealing ball.
Also described is a method of detecting the launching of a device, comprising providing the device with a first component; passing the device through a conduit, the conduit being in fluid communication with an upper end of a wellbore; providing a second component, the first and second components adapted to be in communication with each other as the second component is substantially adjacent the first component; and providing a signal from the first or second component to a host electronics package when the second component is substantially adjacent the first component, thus detecting the launch of the device. The method may further include providing a detectable object for the first component and providing a sensor for the second component.
In some aspects, the method includes providing a transponder for the detectable object and providing a sensor coil for the sensor. Also described is the step of providing a wiper plug with a transponder therein, a first end of the conduit being connected to an upper end of a casing within the wellbore, the sensor coil being adapted to be disposed on a perimeter of the first end of the conduit.
The step of passing the device through a conduit may include passing the wiper plug through a cement manifold, and pumping a fluid down the conduit behind the wiper plug to force the wiper plug into the casing. The method may include providing a sensor coil for the sensor and a transponder adapted to send a Radio Frequency Identification signal from the transponder to the sensor coil.
In some embodiments, the step of providing the device further comprises providing a sealing ball with a transponder therein, a first end of the conduit being connected to the upper end of the casing by an intermediate pipe, the sensor coil being adapted to be disposed on a perimeter of the intermediate pipe. In others, the step of passing the device through a conduit further comprises passing the sealing ball plug through a sealing ball injector.